Nitrous Oxide Sensing using Oxygen-Insensitive Direct-Electron-Transfer-Type Nitrous Oxide Reductase

抄録

Nitrous oxide (N₂O) is known as a greenhouse gas and a dominant ozone-depleting substance. It is is released mainly from agricultural processes. Therefore, the development of an on-site monitoring system is required to measure N₂O concentration and control the release from the source. Using oxygen-insensitive cytochrome c-type nitrous oxide reductase, wNosZ, from Wolinella succinogenes, we have developed an electrochemical enzyme sensor. The sensor signal depends on the concentration of N₂O in a reaction cell containing methoxy-5-methylphenazinium methylsulfate (mPMS) as an electron mediator under Ar atmosphere and, surprisingly, under air. Moreover, in the absence of addition of an electron mediator to the reaction cell, we observe that the reduction current depends on the concentration of N₂O, which implies direct electron transfer. The wNosZ electrode is stable when stored at 4°C for 2 weeks and is specific to N₂O. These results suggest that wNosZ holds great promise as a component of a novel direct-electron-transfer-type electrochemical sensing system for N₂O.